Mineral lubricating oil compositions



tnt d 3,007,872 Patented Nov. 7, 1961 MINERAL LUBRICATING URLCOMPQSE'HQNS Arthur Donald Sheliard, Wrexham, North Wales, QhariesNorman Thompson, Wirincs, Donald Keith Gilmour,

Upton Park, Chester, and Robert James Morris, Wailasey, England,assignors to Shell Oil Company, a con poration of Delaware No Drawing.Filed Dec. 5, H57, Ser. No. 700,737

3 Claims. (Cl. 252-48.6)

This invention relates to an improved process for hnproving theproperties of hydrocarbon lubricating oils. More particularly it relatesto a process for the preparation of improved lubricating oil additivesand to hydrocarbon lubricating oils containing added amounts of suchadditives and having enhanced properties.

An important factor affecting the ability of a mineral lubricating oilto lubricate effectively various machine elements such as in internalcombustion engines, gear etc., is the spreading pressure of the minerallubricating oil on the solid surfaces involved.

It has now been discovered that the spreading pressure of hydrocarbonlubricating oils on solid surfaces can be increased easily andeconomically Without any adverse effects on the chemical or physicalproperties of the oil by treating such lubricating oils containing atleast 5% naturally occurring polyaro-matic and heterocyclic materialstherein and at least 0.1% sulfur with a small amount of aper(carboxylic) acid. More particularly it has been found that whencertain high sulfur-content mineral oil fractions, identified more fullyhereinafter, are treated with an organic per(carboxylic) acid a prodnotis obtained which has a very high spreading pressure on solid surfaces.The product, blended in a hydrocarbon lubricating oil, raises thespreading pressure of the oil on solid surfaces. Moreover, in thetreatment of the high sulfur-content fraction with the peracid, asubstantial portion of the peracid in relation to the oil fraction maybe used. Since the treated mineral oil fraction is normally required tobe added to the base hydrocarbon lubricating oil in only a smallproportion, this use of a substantial proportion of per-acid in thetreatment of the mineral oil fraction does not impair the otherproperties of the finished lubricating oil and does not prove to beuneconomic. Moreover, the sulfur content of the mineral oil fraction isnot substantially changed by the treatment.

The certain high sulfur-content mineral lubricating oil fractions,referred to are either, (1) a mineral lubricating oil aromatic extractcontaining at least 0.2% sulfur and more than 5% polyaromatic andheterocyclic materials or (2) a high sulfur-content (at least 1%)content mineral oil having an initial boiling point of at least 300 C.and a viscosity-gravity constant of at least 0.9. The viscosity gravityconstant is defined by the relation between the viscosity and specificgravity of the oil as follows:

where G=specific gravity of the mineral at 60 F. and V=viscosity of themineral oil at 100 F. in Saybolt Universal units.

It has already been proposed to reduce the sulfur content ofhydrocarbons such as gasoline and the like by treating such hydrocarbonswith peracids which contain the group O-OH and therefore, by hydrolysis,will form hydrogen peroxide, for example, peracids such as peracetic orperpropionic acids. Such prior proposals were designed primarily forsweating gasoline or kerosene by removing sulfur compounds from them,and involve the use of substantial proportions of peracids, and were notconcerned with improving lubricating oils or with the manufacture oflubricating oil additives. On the other hand, in the process of thepresent invention, only a small proportion, not more than 1.5% byWeight, of the peracid is used when treating the lubricating oil toimprove the oil directly, or a larger amount of peracid is used whenapplying it to the treatment of certain oil fractions as alreadydefined. When the treatment is practiced in accordance with the presentinvention there is little, if any, reduction in the sulfur content ofthe treated oil. Furthermore, the sulfur-containing compounds areconverted into more effective lubricating oil components having the samenumber of sulfur atoms per molecule, but in different chemicalcombination, and containing a smaller atomic proportion of carbon whilemaintaining it at a large number per molecule, thereby providingmoditied compounds in which the sulfur atoms are in more effectivechemical combination and oxidatively unstable organic groups are removedto produce a more stable product.

The present process may be applied to any type of mineral lubricatingoil having an initial boiling point of about 300 (3., and which containat least 0.1%, and preferably above 0.2%, even better at least 1%sulfur, and at least 5% polyaromatic and heterocyclic materials. The oilmay be derived from a naphthenic, parafiinic or asphaltic crudepetroleum. Generally, when applied as a minor treatment with not over1.5% peracid, it can be applied to mineral lubricating oils of this typewhich have been refined by one of the conventional refining treatments,such as sulfuric acid or oleum treatment, earth or lime treatment, orsolvent extraction with a selective solvent for the aromatic components.It is applicable to parafiinic-type lubricating oil, e.g., lubricatingoils derived from Pennsylvania, Mid-Continent and West Texas crude oilsand lubricating oils derived from other sources which may have had theirparafiinicity increased by solvent extraction with selective solventsfor the aromatic components.

Oil additives can be prepared by the process of the invention bytreating already defined fractions 1) and (.2), with peracids to formoil-soluble high molecular weight sulfones and sulfoxides and mixturesthereof having an oil solubility of at least 1% and being thermallystable up to about 250 C., and having a molecular weight between about300 and about 1000.

The aromatic extract oil fraction (1) is one containing sulfur and maybe the whole of an aromatic extract or one or more portions thereof,such as a distillate fraction or a fraction isolated by an absorptionprocess. Such romatic extracts can be obtained by any suitable means.The extraction of mineral oils with solvents capable of selectivelyextracting the aromatic constituents of such oils is a well-establishedrefinery process and any arematic extract produced in such a process maybe used as starting material for making the additives of the presentinvention. Typical solvents used to extract mineral oils are liquidsulfur dioxide, phenol, furfural, nitrobenzene, cresol, aniline andbeta-beta-dichlor-diethyl ether. Mixtures of solvents are also used, forexample, a mixture of liquid sulfur dioxide and benzene, and a mix tureof propane, cresol and phenol. The mineral oil which is subjected toextraction may be any such oil having a substantial aromatic content andis preferably a mineral lubricating oil, although it may be, forexample, a kerosene, gas oil or a cycle oil from a catalytic cracking prcess. Preferred aromatic extracts for use in this invention are thoseobtained by extracting a mineral lubricating oil having a viscosity of30 to 500 seconds Redwood I at F. with liquid sulfur dioxide, furfural,phenol or a mixture of propane, cresol and. phenol.

The oil fraction (2) useful for preparing oil additives by the processof the invention are residual and distillate mineral oil fractionshaving an initial boiling point of at least 300 C., a viscosity-gravityconstant (VGC) of at least 0.9 and a sulfur content of at least 1% byweight. These mineral oil fractions may be obtained from crude petroleumoils, either as residue or distillate, by distillation, e.g.,distillation at atmospheric, sub-atmospheric or super-atmosphericpressure, and steam distillation. The fraction may have been partiallyrefined, e.g., by deasphalting with propane or butane. Preferred mineraloil fractions are those having a viscosity-gravity constant above 0.95and those having a sulfur content between 5 and 20% by weight.

Crude petroleum oils, from which the above mineral oil fractions may beobtained, are available from a variety of sources and examples ofsuitable crudes are given in Table I with typical values of the sulfurcontent, viscosity and gravity characteristics for samples of the crude.Residual mineral oil fractions suitable for treatment according to thepresent may be obtained from crude sources having a sulfur content below1% since normally on distillation the sulfur compounds concentrate inthe residual fraction.

A particularly preferred mineral oil fraction for treatment according tothe process of the present invention is a residual mineral oil fractionderived from a semi-solid bituminous Utah crude petroleum. Typicallysuch a fraction has the following characteristics:

Sulfur content percent by weight Specific gravity Viscosity in SayboltUniversal seconds at 100 F approximately 10,000 Viscosity-gravityconstant 0.96

Suitable organic peracids which may be used according to the presentinvention are the peracids of the lower fatty acids, such as performicacid, peracetic acid, perpropionic acid and perbutyric acid, theperacids of the substituted lower fatty acids, such asmonochlorperacetic acid and trichloiperacetic acid, and the peracids ofthe aromatic carboxylic acids, such as perbenzoic acid. Of these,performic acid and trichlorperacetic acid are the most eifective,and-performic acids is preferred.

The peracids may be used in the present process either as such or instatu nascendi. Thus, instead of treating the mineral oil or fractionsthereof with a preformed organic peracid, the mineral lubricating oil orfractions thereof, as defined, may be treated with a mixture of theorganic acid and hydrogen peroxide. When using a mixture of an organicacid and hydrogen peroxide, these reagents may be used in stoichiometricproportions but generally it is preferable to employ excess of the acid.

The treatment of the mineral oil and fractions thereof with the peracidis generally eifected at ambient temperature, although any otherconvenient temperature, such as between and 100 C., may be employed. Themineral oil or fractions thereof and the peracid should be well agitatedto ensure intimate contact and, with good agitation, the reaction shouldbe completed in a period of from to 60 minutes. With large scalebatches, agitation for longer periods, such as up to 2 or 4 hours, maybe necessary. The proportions of peracid employed may vary widely anddepends on the oil being treated. Thus, when the oil is used rather thanfraction (1) or (2), the amount of peracid used should not amount tomore than 1.5% by weight of the oil. In general, a proportion of between0.5 and 1% by Weight will be used, although where only small increasesin spreading pressure are required, much smaller quantities, e.g., 0.5to 0.5% by weight, may be used. When either fraction (1) or (2) is used,the amount of peracid may be between 2 and 25%, more usually between 5and 20%, by Weight, based on the petroleum fraction treated, althoughwhere only small increases in spreading pressure are required, muchsmaller quantities, for example, 0.1 to 1.0% by weight, may be used.

It is sometimes convenient, for example, when the mineral oil fraction(1) or (2) is a viscous one, to dilute the mineral oil fraction with athinner oil or solvent before treatment with the peracid. Thus, it maybe diluted with thin lubricating oil, gas oil or kerosene or a solventsuch as xylene, toluene or petroleum ether.

A convenient method of efiecting the treatment is to mix the mineral oilor fractions thereof with the necessary proportion of an aqueoussolution of hydrogen peroxide and with the organic acid. The hydrogenperoxide solution is conveniently used in the form in which it isreadily available commercially, for example as 100- volume hydrogenperoxide which contains 30% by weight of hydrogen peroxide. Similarly,the organic acid is conveniently used in the form in which it isavailable commercially. Thus, formic acid may be used as the commercialacid containing by volume of H.COOH, whereas acetic acid can be used asglacial acetic acid. More dilute aqueous solutions of formic acid may beused, such as those containing 20 to 50% by volume of H.COOH. In thecase of solid organic acids such as trichloracetic acid, these may bedissolved in a suitable solvent such as Water or a low boiling alcoholbefore adding to the mineral oil or fractions thereof and hydrogenperoxide solution, or they may be dissolved or dispersed in the hydrogenperoxide solution or in the mineral oil fraction before mixing with themineral oil fraction or hydrogen peroxide solution, respectively.

After the treatment with the peracid, the mineral oil or fractionsthereof will generally require working up to remove residual acid,hydrogen peroxide and water. This may be effected by simple waterwashing or washing with an aqueous or alcoholic solution of an alkalinematerial, such as caustic soda or sodium carbonate or ammonia. The lasttraces of water may be removed from the treated and washed mineral oilfraction by azeotropic distillation with a volatile solvent such asbenzene, toluene or xylene. Alternatively, after the treatment with theperacid, the aqueous phase is removed and a solid alkaline material,such as sodium carbonate or lime, is added to the mineral oil fractionand the mixture is filtered. A mixture of sodium carbonate and anactivated earth, such as is normally used in the finishing oflubricating oils, is also a suitable solid alkaline material.

The following examples illustrate the process for preparing improvedfinished mineral lubricating oils of the present invention which may beused as such or blended with other lubricating oils prior to use.

EXAMPLE 1 parts by weight of a solvent-refined mineral lubricating oilhaving a viscosity of 330 seconds Redwood I at F. and a spreadingpressure on steel of 7.7 dynes per centimeter was mixed with one part byvolume of formic acid (90% by weight H.COOH) and 0.5 part by volume of100-volume hydrogen peroxide solution, and the whole stirred for 2 hoursat room temperature. The treated oil was washed with water and twicewith an equal volume of a 3% by weight aqueous caustic soda solution,followed by a final water wash. The finished oil had a spreadingpressure on steel of 18.3 dynes per centimeter.

The analytical data on the untreated and treated oil was as follows:

A Pennsylvania 150 neutral lubricating oil which had a sulfur content ofless than 0.1% by weight and a spreading pressure on steel of 15.2 dynesper centimeter was treated as in Example 1. The finished oil had aspreading pressure on steel of 27.2 dynes per centimeter.

EXAMPLE 3 A naphthenic lubricating oil having a sulfur content of 1.0%by weight and a spreading pressure on steel of 13.1 dynes per centimeterwas treated as in Example 1. The finished oil had a spreading pressureon steel of 20.4 dynes per centimeter.

EXAMPLE 4 60 gallons of a solvent-refined mineral lubricating oil havinga viscosity of 330 seconds Redwood I at 140 F., a sulfur content of0.66% and a spreading pressure on steel of 7.8 dynes per centimeter wasstirred at room temperature for 2 hours with 0.5 by volume of 100-volumehydrogen peroxide solution and 1% by volume of formic acid (90% byweight I-LCOOH). The oil was then mixed with 2% by weight of lime and 2%by weight of an activated earth, stirred for one hour and filtered. Thefiltered oil was again treated for 2 hours with 0.5% by volume of100-volume hydrogen peroxide solution and 1% by volume of formic acid(90% by Weight H.COOH) and lime and earth-treated as in the first stageand again filtered. The finished oil had a sulfur content of 0.65% and aspreading pressure on steel of 18.3 dynes per centimeter.

EXAMPLE 5 100 parts by weight of a solvent-refined mineral lubricatingoil having a viscosity of 330 seconds Redwood I at 140 F., and aspreading pressure on steel of 7.8 dynes per centimeter were stirred for2 hours with 1 part by volume of 100-volume hydrogen peroxide solutionand 1 part by volume of formic acid (90% by weight H.COOH) at roomtemperature. The mixture was stirred with 1% by weight of an activatedearth and 1% by weight of lime for 30 minutes and then filtered. Thefinished oil had a spreading pressure on steel of 19.1.

EXAMPLE 6 100 parts by weight of the solvent-refined mineral lubricatingoil used as starting material in Example 5 were stirred for 2 hours with1 part by volume of 100-volume hydrogen peroxide solution and 1.25 partsby volume of glacial acetic acid. The mixture was then stirred with 2%by weight of activated earth and 2% by Weight of lime for 30 minutes andthen filtered. The finished oil had a spreading pressure on steel of14.1 dynes per centimeter.

EXAMPLE 7 Example 6 was repeated using 1.5 parts by volume of propionicacid in place of the acetic acid. The finished oil had a spreadingpressure on steel of 16.0 dynes per centimeter.

EXAMPLE 8 Example 6 was repeated using 2 parts by volume of butyric acidin place of the acetic acid. The finished oil had a spreading pressureon steel of 16.6 dynes per centimeter.

EXAMPLE 9 Example 6 was repeated using 0.25 gram mols of monochloraceticacid in place of the acetic acid. The finished oil had a spreadingpressure on steel of 16.5 dynes per centimeter.

EXAMPLE 10 Example 6 was repeated using 0.25 gram mols of trichloraceticacid in place of the acetic acid. The finished oil had a spreadingpressure on steel of 17.6 dynes per centimeter.

EXAMPLE 11 The processof Example 6 was applied to the treatment of fourdiiierent mineral lubricating oils obtained as raffinates from thecresylic acid-propane duosol extraction of mineral lubricating oilfractions. The viscosities of the oils, their initial spreading pressureon steel and their spreading pressure on steel after bieng subjected tothe process are set out in Table 11:

TABLE II Spreading Spreading Viscosity in seconds Redwood I at pressureon pres-sure on 140 F. steel of steel of untreated oil, treated oil,dynes/cm. dynes/cm.

EXAMPLE 12 The process of Example 5 was repeated on six differentmineral lubricating oils obtained as rafiinates from the furfuralextraction of mineral lubricating oil fracitons. The viscosity of thetreated oils and their spreading pressure on steel before and aftertreatment is set out in Table III.

TABLE III Spreading Spreading Viscosity in seconds Redwood I at pressureon pressure on 140 F. steel of steel of untreated oil, treated oil,dynes/em. dynes/cm.

The analytical data on the untreated and treated oil (65 secondviscosity in Redwood I at 140 F.) was as follows:

Untreated Treated Nitrogen 0. 01 0. 01 Cale. molecular formula-CsmoHsdsOmssmr Cz8H54.7O1.35S g0 Sulfoxide, moles kg 0. 2 1.65

Suttone, moles/kg. None 0. 15

The following examples illustrate the process of preparing lubricatingoil additives from aromatic extracts (1).

EXAMPLE 13 The aromatic extract used in this example was prepared byextracting a Venezuelan naphthenic spindle oil distillate having aviscosity of 45 seconds Redwood I at 140 F. with liquid sulfur dioxideand removing the sulfur dioxide from the extract. This aromatic extracthad a viscosity of 51 seconds Redwood I at 140 F. 100 parts by weight ofthis aromatic extract were mixed with 1 0 parts by volume of formic acidby weight HCOOH) and 5 parts by volume of -volume hydrogen peroxidesolution and the whole stirred for 3 hours at 20 C. The treated oil waswashed with water until 7 neutral and the oil finally dried byazeotropic distillation with benzene.

To a mineral lubricating oil which had been refined by the Duosolprocess and which had a viscosity of 330 seconds Redwood I at 140 F. anda spreading pressure on steel of 9 dynes per centimeter was added 1% byweight of the peracid treated aromatic extract. The resultinglubricating oil had a spreading pressure on steel of 13.3 dynes percentimeter. When 4% by weight of the treated aromatic extract was used,the resulting lubricating oil had a spreading pressure on steel of 19.2dynes per centimeter, and, when 8% of the treated aromatic extract wasused, the resulting oil had a spreading pres sure on steel of 23.8 dynesper centimeter (Composition 13).

EXAMPLE 14 50 parts by weight of the performic acid-treated aromaticextract prepared as in Example 13 were mixed with 10 parts by volume offormic acid (90% by weight H.COOH) and parts by volume of 100-volurnehydrogen peroxide solution and the whole stirred for 3 hours at 20 C.The product was washed with water until neutral and the treated oildried by azeotropic distillation with benzene.

When 4% by weight of this product was added to the mineral lubricatingoil referred to in Example 13, the resulting lubricating oil had aspreading pressure on steel of 23.6 dynes per centimeter and, when 8% byweight of the product was used, the resulting lubricating oil had aspreading pressure on steel of 25.1 dynes per centimeter (Composition14).

EXAMPLE 15 200 parts by weight of the aromatic extract referred to inExample 13 were mixed with 8 parts by volume of formic acid (90% byweight H.COOH) and 8 parts by volume of 100-volume hydrogen peroxidesolution and stirred for 2 hours at room temperature. A further 8 partsby volume of the formic acid and of the hydrogen peroxide solution werethen added and stirring continued for a further 2 hours. 8 parts byvolume of the hydrogen peroxide solution were then added and stirringcontinued for 2 hours and then a further 8 parts by volume of a hydrogenperoxide were added and the stirring continued again for 2 hours. Theaqueous layer was separated off, and the oil was washed with water untilneutral and the dried by azeotropic distillation with benzene.

When 2% by weight of the above product was blended into the minerallubricating oil described in Example 13, the spreading pressure on steelof the resulting lubricating oil was 19.6 dynes per centimeter(Composition l).

EXAMPLE 16 200 parts by weight of the aromatic extract referred to inExample 13 were mixed with 8 parts by volume of formic acid (90% byweight H.COOH) and 8 parts by volume of IOU-volume hydrogen peroxidesolution and stirred for one hour at 80 C. A further 8 parts by volumeof the formic acid and of the hydrogen peroxide solution were then addedand stirring continued for a further hour at 80 C. 8 parts by volume ofthe hydrogen peroxide solution were then added and stirring continuedfor 2 hours at 80 C. The aqueous layer was separated off and the oilwashed with water until neutral. The product was then dried byazeotropic distillation with benzene.

When 2% by weight of the above product was blended into the minerallubricating oil referred to in Example 13, the spreading pressure onsteel of the resulting lubricating oil was 20.2 dynes per centimeter(Composition 16).

EXAMPLE 17 Example 16 was repeated up to the point where the aqueouslayer was separated off from the treated aromatic extract. After theseparation of this aqueous layer, the treated aromatic extract was mixedwith solid sodium carbonate in a small excess over the quantitynecessary to neutralize the excess acidity in the aromatic extract,together with 1% by weight of activated earth. The mixture was stirredand filtered.

To a mineral lubricating oil having a viscosity of 330 seconds Redwood Iat 140 F. and a spreading pressure on steel of 8 dynes per centimeter,there was added 2% by Weight of the resulting performic acid treatedaromatic extract. The finished lubricating oil had a spreading pressureon steel of 19.2 dynes per centimeter (Composition 17).

EXAMPLE 18 The aromatic extract used in this example was obtained byextracting a Venezuelan neutral naphthenic lubricating oil distillatehaving a viscosity of 230 seconds Redwood I at 140 F. with liquid sulfurdioxide and removing the latter from the extract. This aromatic extracthad a viscosity of 550 seconds Redwood I at 140 F. 100 parts by weightof this extract were diluted with 50 parts by weight of a lightpetroleum spirit (boiling range 60 to C.) in order to reduce itsviscosity. The diluted extract was mixed with 10 parts by volume offormic acid by weight H.COOH) and 5 parts by volume of -volun1e hydrogenperoxide solution and the whole stirred for 3 hours at room temperature.It was then washed with water until neutral and the petroleum spirit andwater were removed by distillation under vacuum.

When 1% by weight of the above product was added to the minerallubricating oil referred to in Example 13, the resulting lubricating oilhad a spreading pressure on steel of 16.9 dynes per centimeter. When 4%of the product was so added, the resulting lubricating oil had aspreading pressure on steel of 19 dynes per centimeter (Composition 18).

EXAMPLE 19 A heavy cycle oil from a fluidized catalytic crackingprocess, which cycle oil had a viscosity of 67 seconds Redwood I at 100F., was extracted with furfural and the extract phase distilled. Thefraction boiling from 200 to 250 C. at 20 mm. of mercury pressure wastaken as the aromatic extract for this example.

10 parts by weight of this aromatic extract were mixed with 5 parts byvolume of formic acid (90% by weight H.COOH) and 5 parts by volumel00-volume hydrogen peroxide solution and the whole stirred for 2 hoursat room temperature. A further 5 parts by volume of each of the formicacid and the hydrogen peroxide solution were then added and the mixturestirred for a further 4 hours. The mixture was then washed with wateruntil neutral. An equal volume of benzene was added and theextract/benzene blend was added to a mineral lubricating oil having aviscosity of 33 0 seconds Redwood I at F. and a spreading pressure onsteel of 18 dynes per centimeter in such a proportion that the finishedoil would contain 2% by weight of the treated aromatic extract. Thebenzene was stripped 01f from the resulting mixture together withresidual water and the finished lubricating oil was found to have aspreading pressure on steel of 25 dynes per centimeter.

EXAMPLE 20 A'sulfuric acid treated transformer oil extract fraction wastreated with performic acid in two stages using each.

Analytical data and infrared spectroscopic estimations of sulfoxide andsulfone concentrations for the treated and untreated extracts were:

The increase in oxygen content (measured directly) during treatment is1.0/gram-atom per kilogram; thus 85% of the oxygen added by performicacid treatment has entered into sulfone and sulfoxide linkages.

The following examples illustrate the process of making lube oiladditives from high sulfur-content mineral oil fractions (2) having aninitial boiling point of at least 300 C. and a viscosity-gravityconstant (V6C) of at least 0.9.

EXAMPLE 21 200 parts by weight of a residual mineral oil fractionderived from a semi-solid bituminous Utah crude petroleum which fractionhad an initial boiling point of 370 C., a sulfur content of 12% and aviscosity-gravity constant of 0.96, were mixed with 200 parts by Weightof a hydrocarbon oil having a boiling point between 60 and 80 C. andagitated for 4 hours at 20 C. with 8 parts by volume of 100-volumehydrogen peroxide and 16 parts by volume of formic acid (90% HCOOH). Thetreated mineral oil fraction was washed with water until neutral andfinally dried by azeotropic distillation with benzene. The sulfurcontent of the treated mineral oil fraction was 12%.

The treated mineral oil fraction was added in the proportion of 1% byweight to a mineral lubricating oil, which had bee refined by the Duosolprocess and had a viscosity of 330 seconds Redwood I at 140 F. and aspreading pressure on steel of 9 dynes per centimeter. The spreadingpressure on steel of the lubricating oil after addition of the treatedmineral oil fraction was 23 dynes per centimeter (Composition 21).

EXAMPLE 22 100 parts by weight of a mixture comprising a residualmineral oil fraction derived from a semi-solid bituminous Utah crudepetroleum, having a sulfur content of 12%. a viscosity-gravity constantof 0.96 and an initial boiling point of 350 C., and a minerallubricating oil having a viscosity of 60 seconds Redwood I at 140 F. inwhich the sulfur content of the resulting mixture Was 1.8%, was treatedat 90 C. for one hour with a mixture of parts by volume of 100-volumehydrogen peroxide solution and parts by volume of formic acid (90%HCOOH). A further 5 parts by volume of hydrogen peroxide and 10 parts byvolume of formic acid were then added to the mixture and agitated for afurther period of one hour. The resulting liquid was mixed with another5 parts by volume of hydrogen peroxide and 10 parts by volume of formicacid and agitated again for an hour. The treated hydrocarbon oil mixturewas Washed with water and dried by azeotropic distillation with benzene.

To a mineral lubricating oil which had been refined by the Duosolprocess and having a viscosity of 330 seconds Redwood I at 140 F. and aspreading pressure on steel of 9 dynes per centimeter was added 1% ofthe above treated Utanol mixture and the resulting lubricating oil had aspreading pressure on steel of 11.0 dynes per centimeter. When 7% byweight of the treated mixture was added to the mineral lubricating oilthe resulting lubricating oil had a spreading pressure of 21 dynes percentimeter (Composition 22).

in the above examples the active components present in the oils afterthe peracid treatment were separated 10 by elution chromatography onsilica gel and on infrared spectroscopic inspection were found to besulfoxides and sulfones, predominantly sulfoxides, containing athiophenic structure such as hydrogenated thiophenic, benzothiophenicand dibenzothiophenic structures and having a molecular weight in therange of 300 to 1000.

In addition to improving the spreading pressure of lubricating oils andoil compositions in the manner described, their oxidation stability andcleanliness properties are also greatly improved. To show that peracidtreated mineral lubricating oils and oil compositions containing peracidtreated petroleum fractions of such are more stable and resistant tosludging and lacquer formation than untreated oils, the oils and oilcompositions identified below were subjected to the Dornte OxidationTest (catalyst, Cu 10 ppm. and Fe 10 ppm, temperature 150 C.) and theHercules -hour cycling singlecylinder engine test and the results wereas follows.

Mineral lubricating oils of examples such as Examples 1, or 4 to 12 whenuntreated had a Dornte time for uptake of 1500 ml. of oxygen per 100 g.oil of about 100 minutes, whereas the peracid treated oils of Examples 1or 4 to 12 gave values of above 1.40. The Hercules Engine overallcleanliness rating (l00=perfect, 0=heavy sludge) of the untreated oilsof Examples 1 and 4 to 12 were around 56 whereas for the peracid treatedoils of Examples 1 and 4 to 12 gave a rating of around 74. Examples 14to 22 when untreated and compositions 13, 14, 15, 16, 17, 18 and 20containing no peracid treated petroleum fractions in the Dornte andHercules engine tests indicate no improvement in spreading pressure orengine cleanliness whereas the corresponding peracid treated oils(Examples 14-22) or oils containing peracid treated petroleum fractions(Compositions B-l8 and 20) indicate improvement in oxidation stability,engine cleanliness and increase in spreading pressure.

If low molecular weight sulfones having an oil solubility of less than1% such as diamyl or dicyclohexyl sulfones or sulfoxides or sulfur-freeoxidized aromatics (oxidized amyl naphthalene) are used in Compositions13-18 or 20 for the peracid treated aromatic extract or peracid treatedresidual oil fractions, the spreading pressure of such compositionsremain the same as that of the base oil in the Dornte oxidation test andHercules engine test the results are the same as for the base oil,namely about 100 (Dornte oxidation test) and 56 for the overallcleanliness rating in the Hercules engine test.

Hydrocarbon lubricating oils produced in accordance with the presentinvention may be blended with fatty oils, such a rape seed oil and lardoil, or with synthetic lubricating oils or mixtures of syntheticlubricating oils and fatty oils. Synthetic lubricating oils which can beblended with hydrocarbon lubricating oils which contain treated mineraloil fractions according to this invention, include those produced bypolymerization of olefins or by the allrylation of aromatic hydrocarbonswith oletins or alkyl halides in the presence of a Friedel-Craftscatalyst, organic ester lubricating oils, such as the dialkyl esters ofdicarboxylic acids, for example, di(2-ethylhexyl) sebacate or adipate,and the alkyl or alkaryl esters of inorganic acids, for example,trioctyl or tricresyl phoshate and tetraoctyl silicate, polymers orcopolymers of pol yalkylene glycols and the esters and ethers thereofand polyorganosiloxanes.

We claim as our invention:

1. A mineral lubricating oil having therein from about 1% to about 8% tostabilize the oil and increase the spreading pressure of the oil, of anadditive prepared by contacting a petroleum fraction selected from thegroup consisting of (1) an oxygen and sulfur containing aromatic extractfraction of a mineral oil, said fraction having a sulfur content of from0.2% to 1% and containing a minimum of 5% naturally occurringpolyaromatics and heteroincorporated by weight suflicient cyclicmaterials and (2) a mineral oil having an initial boiling point of about300 C., a viscosity gravity constant of 0.9-0.95 and a sulfur content offrom about 1% to about 20% with from 2% to 25% by weight of performicacid at between and 100 C. for from minutes to 3 hours, said treatmentresulting in essentially no change in the sulfur content of the treatedpetroleum fraction.

2. A mineral lubricating oil having incorporated therein from about 1%to about 8% by weight sufiicient to stabiiize the oil and increase thespreading pressure of the oil, of an additive prepared by contacting anoxygen and sulfur-containing aromatic extract fraction of a mineral oilfraction, said fraction having a sulfur content of from about 0.2% toabout 1% and containing a minimum of 5% naturally occurringpolyarornatics and heterocyclic materials with from 2% to 25% by weightof performic acid at between 0 and 100 C. for from 5 minutes to 3 hours,said treatment resulting in essentially no change in the sulfur contentof the treated aromatic extract fraction.

3. A mineral lubricating oil having incorporated therein from about 1%to about 8% by weight sufficient to stabilize the oil and increase thespreading pressure of the oil, of an additive prepared by contacting anoxygen and sulfur containing mineral oil fraction having an initialboiling point of at least 300 C., a viscosity gravity constant of 09-095and a sulfur content of from about 1% to about with from 2% to by weightof performic acid at between 0 and C. for from 5 minutes to 3 hours,said treatment resulting in essentially no change in the sulfur contentof the treated aromatic extract fraction.

References Cited in the file of this patent UNITED STATES PATENTS1,967,255 Penniman July 24, 1934 1,972,102 Malisoff Sept. 4, 19342,004,849 Bretschger June 11, 1935 2,218,618 McNab et al. Oct. 22, 19402,749,284 Noble June 5, 1956 FOREIGN PATENTS 758,567 France Nov. 3, 1933OTHER REFERENCES Kalichevsky et al.: Petroleum Refining with Chemicals,Elsevier Pub. Co., N.Y., 1956, page 23.

1. A MINERAL LUBRICATING OIL HAVING INCORPORATED THEREIN FROM ABOUT 1%TO ABOUT 8% BY WEIGHT SUFFICIENT TO STABILIZE THE OIL AND INCREASE THESPREADING PRESSURE OF THE OIL, OF AN ADDITIVE PREPARED BY CONTACTING APETROLEUM FRACTION SELECTED FROM THE GROUP CONSISTING OF (1) AN OXYGENAND SULFUR CONTAINING AROMATIC EXTRACT FRACTION OF A MINERAL OIL, SAIDFRACTION HAVING A SULFUR CONTENT OF FROM 0.2% TO 1% AND CONTAINING AMINIMUM OF 5% NATURALLY OCCURRING POLYAROMATICS AND HETEROCYCLICMATERIALS AND (2) A MINERAL OIL HAVING AN INITIAL BOILING POINT OF ABOUT300*C., A VISCOSITY GRAVITY CONSTANT OF 0.9-0.95 AND A SULFUR CONTENT OFFROM ABOUT 1% TO ABOUT 20% WITH FROM 2% TO 25% BY WEIGHT OF PERFORMICACID AT BETWEEN 0* AND 100*C. FOR FROM 5 MINUTES TO 3 HOURS, SAIDTREATMENT RESULTING IN ESSENTIALLY NO CHANGE IN THE SULFUR CONTENT OFTHE TREATED PETROLEUM FRACTION.